The Elements of economic geology

Bibliographic data

Monograph

Identifikator:: 1773832379

URN:: urn:nbn:de:zbw-retromon-172798

Document type:: Monograph

Author:: Gregory, John W. http://d-nb.info/gnd/11683014X

Title:: The Elements of economic geology

Place of publication:: London

Publisher:: Methuen

Year of publication:: 1928

Scope:: XIV, 312 S.; graph. Darst.

Digitisation:: 2021

Collection:: Economics Books

Usage license:: Get license information via the feedback formular.

Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: Part I. Introduction

Collection:: Economics Books

ECONOMIC GEOLOGY by tension, as when a sheet of rock is stretched by folding, or shrinks during cooling or drying. The second kind of fissures are formed along faults, i.e. where the rock on one side of a fracture has been moved along it. Faults are usually marked by slickensides or scratches on the walls, and by a rubble of rock fragments known as fault-breccia. Pug or fluccan (Cornish) or gouge (American) is material that has been ground by the movement into clay. Faults are usually not quite straight, but curve around harder layers or masses. Owing to the curves the fault fissure usually consists of lenticular Spaces, separated by the pro- jections of the opposite walls coming into contact. The lode or vein along such a fault alternately expands and contracts and may consist of isolated lenticles of ore. A lode in which the sides are not parallel is known as a block-lode or wavy- lode (Fig. 2) ; where the lode widens it is said *‘ to make ; " where it contracts it is said to ““ pinch * or “ peter.” The ‘hin streak along part of a fault plane »n which there may be no lode matter, sxcept perhaps a film of pug, is said to be the “lode track,” as the miner ex- pects it to lead him to the next * make” of ore. If a fault crosses a series of bedded rocks the fractures may be diverted here and there along a bedding plane, and the lode may therefore be repeatedly deflected and may consist of steps; such step-lodes may be due to a series of faults. Either the part along or across the bedding plane may be represented by a lode track, and the actual lode be reduced to a series of parallel isolated sections. A vein parallel to the bedding of the rocks is a bedded- vein, a vein transverse to the country, if confined to one bed, is a gash-vein, but if it cut across several beds, it is a rake-vein. Lodes are usually steeply inclined ; if horizontal they are often known as “floors.” If formed along more or less horizontal faults they are sometimes known as “slides.” Floors often occur one below another in a dyke or narrow intrusion of igneous rock ; these floors are formed along

Access restriction

Copyright

fullscreen: The Elements of economic geology

Monograph

Chapter

Table of contents

Download

Monograph

Chapter

This page

Image fragment

Citation links

Citation recommendation